MPPC at T2K

南野彰宏（京都）
第3回次世代光センサーに関するワークショップ@ 名古屋大学
Dec. 18, 2010

The T2K collaboration
The T2K Collaboration~500 members, 61 Institutes, 12 countries
Italy
Canada
INFN, U. RomaTRIUMF
U. Alberta
INFN, U. Napoli
U. B. ColumbiaINFN, U. Padova
U. Regina
INFN, U. Bari
U. Toronto
U. Victoria
Japan
York U.
ICRR Kamioka
ICRR RCCNFranceCEA Saclay KEK
IPN Lyon
Kobe U.
LLR E. Poly.
Kyoto U.
LPNHE Paris
Miyagi U. Edu.
Osaka City U.
Germany
U. Aachen
U. Tokyo

PolandA. Soltan, Warsaw
H.Niewodniczanski,Cracow
T. U. Warsaw
U. Silesia, Katowice
U. Warsaw
U. Wroclaw

Spain
IFIC, Valencia
U. A. Barcelona

RussiaINR

United Kingdom
Imperial C. London
Queen Mary U. L.
Lancaster U.
Liverpool U.
Oxford U.
Sheffield U.
Warwick U.

S. Korea
N. U. Chonnam
U. Dongshin
U. Sejong
N. U. Seoul
U. Sungkyunkwan

Switzerland
U. Bern
U. Geneva
ETH Zurich

STFC/RAL
STFC/Daresbury
USA
Boston U.
B.N.L.
Colorado S. U.
Duke U.
Louisiana S. U.
Stony Brook U.
U. C. Irvine
U. Colorado
U. Pittsburgh
U. RochesterU. Washington
2The T2K experiment• Long baseline neutrino oscillation experiment in Japan• J-PARC: Intense proton accelarator (design value = 750kW)– K2K: 5.2kW, NuMI for MINOS: 400kW, CNGS: 500kW• Super-Kamiokande: Large water cherenkov detector– Fiducial volume = 22.5 kton (c.f. MINOS = 5.4 kton)

3

T2K goals• Measure last unknown mixing angle q13 using nm→neappearance– Potentially open up dCP search in lepton sector• Measure precisely the atmospheric parameters q23and Dm322 using nm→nm disappearance– Is there a symmetry between 2nd and 3rd generation?

4

T2K schematic• Beam monitoring– Primary beam monitors (intensity, position, profile)– Muon monitor (MUMON) after the decay pipe
– On-axis neutrino detector (INGRID) at 280 m from the target• Beam characterization and cross section measurements– (2.5˚) off-axis neutrino detectors at 280 m from the target• Neutrino flavor and flux measurement at far site
– Super-K at 295 km from the target (2.5˚ off-axis)

5

T2K status6

Accumulated protons

Summer shutdown
6→8 bunches
Rep. 3.6→3.2 sec• First run (January to June 2010)– ~50 kW stable operation; 3.23×1019 protons for physics analysis• Second run started on Nov. 16– Rapid ramp up to current 115 kW

7

T2K events in Super-K (1)Jan-June 2010
# of events
Fully-Contained (FC)33+ fiducial volume cut
23+ visible E > 30 MeV (FCFV)Vertex and direction (FC, Evis>30MeV)
Beamdirection

Vertex R vs Z

Vertex X vs Y

FVID wall

FVPoints: Reconstructed event vertex, Arrow: 1st-ring direction

ID wallT2K events in Super-K (2)single-ring m-like

multi-ring m-like

Pm = 1061 MeV/c

Pm = 1438 MeV/c

1 decay-electrons

2 decay-electrons

Expect first results by winter 2011 conferences.

T2K near detectors
and MPPC

10INGRID on-axis neutrino detector• On-axis detector is crucial for off-axis measurements– Monitor beam direction, intensity and mean energy– Beam coverage ~ 10×10 m2– Off-axis angle measurement accuracy goal is 1 mrad (< 15MeV shift on off-axis peak energy)– 10k n interactions per day at full power (750 kW)
INGRID “cross” is formed with
14 identical modules + 2 diagonal
modules made of plastic
scintillator planes and iron targets
surrounded by VETO planes.
11

INGRID measurements# of n events/1e14 POT

Six bunch beam structure

Total # of n events ~ 500k

Beam profile X

Beam profile center X

12

T2K off-axis near detectors• The off-axis near detectors provide– Off-axis beam measurement based on CCQE
– Beam ne contamination– Super-K background measurements (NCp0)– Precise cross-section measurements with very large statistics

ND280

Off-axis
detectors

On-axis detector(INGRID)
13

Off-axis near detectors measurements

14

ND280 photosensor requirements• Operational in magnetic field B=0.2T (UA1 magnet)• Very tight space constraints– Compact• Low light yield at the end of Y-11 fibre (latt = 3.5 m)– Photo detection efficiency > PMT @ 550 nm• Large number of channels (56000)– Low price• Detector operation for five years

15

MPPC development for T2K: a fast R&D!
• 2004-2005: First study of photon-sensor options– MA-PMT, MCP-PMT, APD, GM-APD arrays– First tests of MRS-APD from CPTA by ND280 groups• End of 2005: Decision to use GM-APD arrays– In November, we met with Hamamatsu Photonics K.K.

• 2006: R&D of MPPC by Japanese groups (T2K, ILC etc)
– Other SiPM candidates were also tested• 2007: First MPPC on Hamamatsu catalogue (1×1mm2)• End of 2007: 1.3×1.3mm2 50mm pitch (667 pixels)
ceramic package type MPPC is adopted for all ND280– Delivery of 63500 MPPCs (inc. spares) was completed inFeb. 2009!

16

T2K MPPC specifications
ItemSpec

Active area

1.3 x 1.3 mm2

Pixel size

50 x 50 mm2

Num. of pixels

667

Operationvoltage
PDE @ 550nm

70 V (typical)

Dark count(Gain = 7.5 x 105)

< 1.35 Mcps
@ 25 deg.
(Thre. = 0.5 p.e.)
56,000A. Minamino @ IEEE Dresden 2008

Num. of device

S10362-13-050C
Developed for T2K

1.3 mm~ 25 %

Produced byHamamatsu Photonics
17

MPPC in T2K near detectors

Connectors for INGRID/FGD• Basic element of the neardetector scintillator subsystem(INGRID, P0D, FGD, ECAL, SMRD)– Extruded scintillator bar withembedded Y-11 fibre read out by
individual MPPC in coupler– 56000 channels in total

MPPCY-11 FibreFerrule

Spring foamConnector
PCB board

ShroudConnectors for P0D/ECAL/SMRD
18

Readout electronics
Trip-T electronics••••

64 Hi/Lo gain ADC and TDC
Individual HV trim (8bit, 5V range)
On board charge injection circuit
Temperature sensors
19

Kyoto large scale test (17686 MPPCs)
Mean=4.8×105

66.5-69.7V

Vbd at 20˚C
Mean=0.07
RMS~measure. sys.

Mean=450 kHz

RMS~ measure. sys.

Gain
Mean=1.53
RMS~measure. sys.

Dark rate (kHz)DV = 1.0V and 20˚C
Failure rate < 0.05 %AP + CT prob.

PDE (xPMT)

M. Yokoyama et al.,
NIM A 622 (2010) 567-573

Device uniformity itself is considered to be much better.

20

Bad channels (after ~2 year operation)
SystemChannels

Bad channels

Fraction

ECAL (DSECAL) 22336 (3400)

35 (11)

0.16% (0.32%)

SMRD

4016

70.17%

P0D

10400

70.07%

FGD

8448

200.24 %INGRID

10796

180.17 %

Total

55996

870.16 %Bad channel does not necessarily mean problem with the MPPC,it could be electronics, cable or connection problem as well. 21

MPPC characterization

22

Gain and temperature dependence• Gain proportinal to overvoltage• Breakdown voltage changes with temperature

23

Dark count rate
TA8120TA8120• Dark count is proportional with overvoltage• Increase exponentially with temperature
24

Photon detection efficiency
INR, Imperial College, Sheffield University

TA9445• PDE was measured at different wavelength using Poisson zeroprobability method– Insensitive to crosstalk and afterpulse• PDE=20-25% for green light at nominal gain• Good agreement in variation with wavelength with Hamamatsu25

Pixel to pixel cross talkT=24˚C• Pixel cross talk measured
with optical microscopy set up, fast
amplifier and laser LED– Beam spot width 5mm– 3 specific pixels: corner[1:1], side[1:5]
and inside[5:5] to study position
dependence of cross talk

• Probability scales consistently withrandom crosstalk generation in pixel

26

What next?

27

A Conceptual Design of theT2K-ND280m Detector Upgrade(no relation to the T2K collaboration)

T. Nakaya @ GLA2010
March 28-31, 2010,Tsukuba.

One vagueidea of TN

Magnet (and side MRD)

Magnet (and side MRD)Electron calorimeter

Gas TPC

Fine Grained detector

Lq. Ar TPC

FGD w/ water scintillator

Scintillating fiber camera(1~2mm fiber)

Idea (2010?) ➝ Realization/Operation 2016?~29

A Conceptual Design of theT2K-ND280m Detector Upgrade(no relation to the T2K collaboration)

T. Nakaya @ GLA2010
March 28-31, 2010,
Tsukuba, Japan.

One vagueidea of TN

Magnet (and side MRD)

Huge # of channels (~70000 - 300000) and very tightspace constraints-> Need to develop a new photosensor and its readout electronics-> Monolithic array MPPC is one of the strong candidate.
Magnet (and side MRD)Electron calorimeter

Gas TPC

Fine Grained detector

Lq. Ar TPC

FGD w/ water scintillator

Scintillating fiber camera(1~2mm fiber)

Idea (2010?) ➝ Realization/Operation 2016?~

30

Summary• Development, commercialization and large production of
MPPC for T2K near detectors completed– Very fast R&D and delivery on schedule of 62500 MPPC for
T2K by Hamamatsu with <0.1% of devices rejected by QA– T2K near detectors are the first large scale application ofMPPC to a real experiment• Operation at T2K has been very stable for ~2 years– Very small number of bad channels (<0.2%)

31

Backup32

T2K q13 sensitivity (normal hierarchy)
90% C.L. sensitivity
sin22q23 = 1.0 is assumed.
5×1021 POT ~ 5 years@ full intensity

0.008 @ Dm213=2.5×10-3[ev2], dCP=0

sin22q13 = 0.1# of eventsin 0.35~0.85 [GeV]
Signal… 103
Beam neBG … 13
BG from nm … 1051021 POT MC
Stat. error+ Syst. error for BG subtraction (10%)‫‏‬

T2K atm. parameters sensitivity• Narrow band spectrum centered on oscillation maximum– Good sensitivity to atmospheric parameters• Expected sensitivity

3– Dsin22q23~0.01– Dm223<1.0×10-4eV234

INGRID on-axis neutrino detector• On-axis detector is crucial for off-axis measurements– Monitor beam direction, intensity and mean energy– Beam coverage ~ 10×10 m2– Off-axis angle measurement accuracy goal is 1 mrad (< 15MeV shift on off-axis peak energy)– 10k n interactions per day at full power (750 kW)

First n event
Nov. 22, 2009
20:25:48 JST35

PIAnO• Measure charged p cross section with 10% sys. errors– Traker size: 5×5×5 cm3– 1.5 mm scintillation fibers + MAPMTs– 150–300 MeV p beam at TRIUMF

M. Ikeda @ NNN10, Dec. 13-16, 2010, Toyama

36Pixel to pixel cross talk37